Refrigeration



Sept. 26,1939. L. F; WHITNEY REFRIGERATIVOYN Filed May 11, 1938 2 snats-sheet 1 uml- Sept.

'L. F. WHITNEY REFRIGERATION Filed May 11, 1938 2 Sheets-Sheet 2 4 exists in the system, the eflfects are negligible. tion of the sludge may be also effected by the 40 UNlTE- TM" res artiste.

' REEBIGERATION' Lyman 16. Whitney, Cambridge, Mass, assignor, by mesne assignments, to Stator ilorporation, a corporation oi Rhoda island Application May 1i, lees, Serial No. 207,268

as Qlaims. (oi. 6%115) This invention relate to an improved reirlgerat dulred in the system. A sludge deposit is also lug apparatus oi the general type disclosed iii deleterious since it tends to impede free circula- United States Patent No. 1361,5521 to 'lilastman tlon oi the fluids through pipes. v

' A. Weaver and in my United States Patent No. When it is desirable to operate the cooler at a .d 1,756,802. The present application is a contihuatemperature below 32 F., I prefer to employ an '5 tion-in-par't of my copending application Serial aqueous refrigerant comprising a solution of a No. 171,325, led October 27, fl937.. 1 suitable anti-freeze agent in water. Among The above" identifi d patents'dlsclose a ystem anti-freeze agents are methyl Cellosolve I (the employing water as a refrigerant and mercury as 1110110 methyl other of ethylene l ethylene lo a propellant. While water has very advahtadiamine. and morpholine. in a system having 10 geous characteristics for this purpose, it often is conventional steel walls, llp 'er o u e an with desirable to provide a refrigerant which has a freeze agent which in the major part consists of loweuireezingpoint. Furthermore, while water methyl Cellosolve and. which preferably includes and mercury are liquids which are substantially a minor part oi ethylene diamine. I have found it immiscible under all ordinary conditions, I have that the emplomhent of methyl cellosolve may ag- 1d ioundthat under certain operating conditions l e the cy O the f m t on o a very fine particles of mercury, such as are prodeleterious sludge. (in the other hand, when vided by mercury vapor or by mercury tog, when either e hyl e fl e morphine s contacting water. tend to assume an extremely ployed, either with water alone or with water and w finely dispersed condition in the water to form methyl Cellosolve, the sludge suspension is thintherewith a more or less stable sludge. For ex her and the lu d lim t e capable of W- sinple, when some mercury passes with the water vapor to the refrigerant condenser, a sludge may The, present invention adords improved rehe formed. This sludge drains to the cooler, irigerating systems of this general character in where it may gradually become heavier as more which the formation of sludge may be impeded, 25 sludge is received from the condenser. Furtherand in which sludge which does form may readily more, mercury vapor or fog may occasionally Does be broken up or resolved. The formation of directly from the asplrator mixing chamber into sludge is iinpeded by the application of-heat to direct contact with the water in'the cooler, thus the refrigerant circuit, i. e;, to the duct extending 3m causing the formation of a sludge The terrbetween the aspirator assembly and the refrigerso dency to form sludge is aggravated in a system ant condenser. The sludge which does form colhaving walls of ordinary steel. The proportions lee-ts in the cooler, which preferably has inclined of mercury and water in the sludge may vary lower walls arranged todirect the sludge to a' widely, and the heavier sludge may resemble drain, with which a suitable sludge separator is mud. associated. 35 I call susuension of mercury in water a sludge The separation of sludge into mercury and resuspenslon. Depending upon operating condifrigierant may be efieoted by evaporation of the tions, this suspension may be either lean or rich refrigerant from the sludge, this evaporation bein the mercury. If only a thin sludge suspension ing 'eflected by heat and/or suction. :fl'i'he separa- However, the mercury tends to settle in such a application of pressure. To this end, for exhody of sludge suspension; the settling mercury ample, a suitable duct may be arranged to remay not coalesce, but, rather may form a mud solve the sludge from the cooler so that the sludge like sludge deposit. Should the factors that collects in a relatively high column. Under these M cause the original suspension continue to be conditions, the sludge at the lower part of the present, they cause the formation of further column is subjected to a substantial liquid head,

. sludge suspension from which additional mercury and he refrigerant is q e ou Of this settles, thus augmenting the mud-like deposit. lower part of the column. Accordingly, the sludge When the sludge suspension is relatively riclr in in. the lower part of the column coalesces into mercury, the tendency to form the mud-like demercury, and the refrigerant rises to the upper 5 posit is'increased. Any type Of sludge except a part of the column. If desired, the sludge septhin sludge suspension is deleterious because it orator may involve both the separation of the involves a collection of mercury where it is not sludge by evaporation of the refrigerant and by needed, this materially increasing the total the subjection oi the sludge to a. substantial liquid amount of the relatively expensive mercury rehead.

automatically varied a trap in which a column of propellant substantially balances the difiference between the cooler and condenser pressures, this trap being arranged so'that the height of the propellant column is in response to variations in the pressure differential between the cooler and the condenser.

' arrangement.

(0 second stage aspirators. The first stage aspirator of the liquids in this part of the system showninthis figure;

In the drawings: I Pig. 1 is adiagrammatic view of a refrigerating system of thetype provided by the present invention;

Fig. 2 is a section on line 2-2 of Fig. 1;

Fig. 3 is an enlarged view of the trap assembly mociatedwith the cooler, a typical arrangement being Fig. 4 is a broken isometricview of a portion of the duct between-theaspirator assembly and the .refrigerant condenser; and

, Pig. 5 is a diagrammatic view of a portion of a system similar to that shown in] Fig. l but being provided with an optional sludge separating A system of this type may comprise a boiler i .having a suitable heater, such'as a gas burner as- 'sembly 2, and being provided with a drai't-inducing flue I, only a portion of which is shown in Fig. 1. Mercury vapor passes from the boiler I through the riser pipe I to the branches i and I which are connected respectively to the first and may comprise a nozzle 6 fromwhich mercury vapor passes at high velocity into a mixing chamber I. The latter is connected by a vapor duct 8 'to the cooler or evaporator 'l I.

contain a body of liquid refrigerant, such as water, and a suitable-anti-free'ae ingredient. Va-

from ll through porisdrawnthroughthepipeltothemixing chamber I, and themifxed propellant and refrigerant vapors pass into the funnel II where the refrigerant is compressed and mercury is condensed. This fimnel preferably is provided with I cooiingmeans, suchasfins II.

Condensed mercury flows from th'e' lower' end of the funnel l2 into a drain ll, while the remaining vapor passes into a pipe coil or loop it, which may be provided with coeling fins It and which forms an interstage cooler. The latter is connected through a duct II with the second stagemixingchamberllintowhichastreamof mercury vapor-flows from. the second stage nosale l8. This'propellant stream causes further com-- pression 'of the refrigerant'vapor in the second etagefunnelll. Adrainllreceivescondensed mercury from the funnel 2! and from the drain ll. Compressed refrigerant passes upwardly the duct It to the refrigerant 80. Preferably the duct "is arranged in heat-transfer relation to a warm partofthesystemnichasthefimnelilandthe riser branch. I l.

lnordertoaidtheheatingofduetfttherisa:

branch I'maycarryametal strip i8 welded theretoand-arrangedincloleiuxtapositiontothe pipe (Pig.2). Alsotheplpeflprefer'ablyispro- The cooler may vided with internal fins 26 (Fig. 3). These fins are preferably arranged in spaced, staggered relation within the pipe and enhance the eflect of preventing the formation of sludge. Preferably, as shown in Fig. 3, the fins at the lower part of the pipe may be provided .with openings 21 through which liquid may drain, thus preventing pocketing of liquid in this part of the system.

I have found that the provision of the warm pipe 29 between the aspirator assembly and the refrigerant condenser not only impedes the formation of sludge, but may also substantially pre- 'vent mercury from passing to the condenser. Possibly the formation of sludge may be partly October 29, 193'], discloses a preferred type of condenser. As shown herein, for example, the condenser 30 comprises a conventional pipe assembly with cooling fins 3!. A chamber or drum 32, preferably is located at the end of the condenser ill which is remote frompipe 28. A pipe I! has an open end communicating with this chamber and receives non-condensable gases therefrom. The lower portion of this chamber is connected to a drain or refrigerant return pipe 34 through which condensed refrigerant passes on its way back to the cooler Ii.

The lower end of the pipe 34 is connected to an inclined tube 48, the upper end of which has a vertical continuation 42 that may extend above the level of the liquid in the cooler Ii. Pipe section "has a connection with a downwardly extending pipe which is connected to a duct 44 that also serves as a drain. The lower part of the cooler II is provided with walls which incline downwardly to the drain N, and the latter in the region of its connection to the cooler also preferably has a substantial inclination.

. The dralnpipe 21 for the second stage funnel 18 has a lower end communicating with a small gchamber II to which the lower end of the inclined pipe ll is also connected, while an upwardly in- I clined duct Ii extends from this chamber fl to the chamber '4 of the purger assembly a. This 'bodies of non-condensable gas in the tube 65.

compressing the gas as they move downwardly.

through the tube. The lower end of tube II is immersed in a body of liquid propellant in the well 01, the upper surface of this liquid propellant b g exposed to the atmosphere.

A neturn duct N is disposed about the tube 65 and is-connected to a pipe 51, there being a very small pressure'equalizing vent between the upper part of duct I and the chamber II.- A deflector it prevents gas from rising into the duct II from the lower end of drop tube I.

The arrangement of the spill-over connection between tube ii and chamber it determines the level of the propellant in the trap provided by the lower parts of ducts 34 and II. The condensed propellant received from drains I4 and. 21 passes into the chamber I and from the latter may pass to the spill-over connection, thus being received y thenu se mmt erqrs be iq r 2,174,300 'pei'lant flows through pipe back to the boiler,

of constant height is automatically maintained inthe leg 6i of the trap, while the total static pressure in this log of the trap is provided by this mercury column. plus the condenser pressure thereabove. This static pressure is balanced in the opposite leg of the trap by the mercury in the tube dd below its connection to the duct (it, and by the liquid columns in the respective branches at and. M or this leg, as well as the pressures above these respective columns; The liquid heads in the branches ti and M may be provided by bodies of mercury and liquid refrigerant.

Fig. 3 discloses a typical position of the liquid in the ducts 34 and t2, the lower part of the :duct 34 containing a column of liquid refrigerant,

and the duct 42 containing a column of pro-= pellant above the connection of duct 34 with duct 40. This column of liquid propellant substantially balances the difference between the condenser and cooler pressures. Above the mercury column in pipe 62, there may be a column of liquid refrigerant, from' the top of which refrigerant may spillover into the ductea. As

7 additional refrigerant is received at the lower part of duct 36, the liquid head within this duct becomes sufilcient to depress the mercury so that some of the refrigerant may rise through the mercury in the upper part of inclined duct W and in duct 42. When the dinferencc between the condenser and cooler pressures increases, ad-

ditional mercury received from drain 2''! passes upwardly through duct id and into duct 12, so

that the height of the liquid column balancing the difference between the cooler and condenser pressures is automatically increased in response to an increase in this-pressure diflference. On the other hand, when this pressure difierence decreases, mercury from the duct dfi and upper part of duct 40 moves downwardly, causing memory to overflow at the spill-over connection between the duct 6! and chamber 64. This arrangement permits the trap assembly associated with the wardly a substantial distance below its connection to the trap provided by duct 44. The upper part of the drum 5]! preferably is connected by a vapor duct 10 to the low pressure portion of the system, such as the head of the cooler I I. Thus the upper 'part. of this drum, during normal operation of the system, is subject to the lower pressure of the first stage aspirator head. The drum may also be conveniently disposed adjoining relatively warm parts of the system, such as the upper part of the propellant riser 5 and the head of the sec- 0nd stage aspirator'assembly.

: The first stage mixing chamber 'lis provided with a drain 49 to receive any propellant par-l ticles condensing therein, while the second stage mixing chamber is provided with a corresponding drain 5|, these drains being connected at their lower ends to provide a trap 52. An upwardly inclined duct 53 may extend Irom' the lower part of the drum 5!) to the lower part of the trap 52. The leg of the trap 52 formed by drain 49 is provided with a spill-over connection with a duct 55, the lower part of which provides. a-trap 58 connected to the duct 5?. Accordingly, mercuryfroin the drains 49 and 5t may spill over into the pipe 55 and return from. the latter through the duct 51 to the boiler i.

When sludge collects in the cooler it, it may form a mud-lihe'deposit on the lower walls or? the cooler. Since the cooler is provided with lower walls which slope downwardly toward the pipe it, this heavy mudelilre deposit can drain into the pipe and thence pass into the drum Eli. Since the latter is connected to the low pressure portion of the system and is in a. relatively warrn location, the more volatile part of the heavy sludge, i. e., the refrigerant, is evaporated and drawn into the first stage mixing chamber, while the mercury residue flows downwardly and received by the pipe 53.

Since the drum Eli extends a substantial distauce' below the spill-over connection. between pipes 49 and 55, any sludge in the lower part of this drum is subjected to a substantial "liquid head. This results in a tendency to squeeze refrigerant out of this sludge, so that'the mercury may coalesce.

Thedrum 50 may not only function as a sludge separator but it also is eilective in automatically reducing the rate of evaporation in the cooler when the refrigerant freezes in theupper part of pipe it. Under these conditions, the refrigerant can no longer pass to the cooler but piles up in the tube 34 until it has sumcient head to cause it to displace some oi the mercury in'the shallow trap provided by duct M, and to pass to the drum 59. Since the upper part of this drum is connected by ipe ill to the low pressure portion of the refrig rant circuit, refrigerant vapor is then withdrawn from the drum to as well as from the cooler II by the first stage aspirator. Accordingly, part of the pumping effect of the first stage jet is then being employed in pumping vapor from drum 50, and the rate of evaporation in cooler H is correspondingly reduced so that its temperature rises, thus causing the icewhich has formed in the pipe 44 to melt.

It is evident that the drum 50 always contains a body of mercury and that ordinarily this'mercury may stand at a. level near that of the spillover connection between'ducts 49 and 55. Ac

cordingly, foreignparticles finding their way into this part ofthe system floaton the surface of the mercury body and do not pass out of the drum.

I! preferred, and especially when an anti-freeze agent is employed which does not aggravate sludge formation, a sludge separator 01' the type shown in Fig. 5 may be employed. This figure discloses portions of the aspirator assemblies and a cooler of the general type shown in Fig. 1, these and other corresponding parts being identifled by referencenumerals similar to those in Fig; 1. In accordance with thisembodiment of the invention, however, the lower part of the cooler I I is connected to a large diametered drain I, which receives refrigerant from a duct 3 corresponding to theduct 43 of Fig. 1-. The duct I, however, extends downwardly a substantial distance below its connection to the tube 3 to permit the collection of sludge in a relatively high column, so that sludge at the lower part of duct I is subjected to a substantial liquid head. Accordingly, the sludge as it moves downwardly and is subjected to this head, is so squeezed that refrigerant is separated from propellant.

The coalesced mercury passes downwardly from the bottom of the duct I into a trap I". This trap may be provided by a tube of smaller diameter than theduct I, since the coalesced mercury will readily pass through a tube of smaller diameter than will the mud-like sludge.

The trap I is provided with a spill-over connection I" with the first stage drain 49, from which mercury overflows through the duct 55 and thus passes back to the boiler.

It is evident that the present invention provides means impeding the formation of sludge in a refrigerating system of the type described, and that the invention also provides means for separating sludge that does form in such a sys-t tern. For the first-named purpose not only may a sludge inhibitor, such as ethylene diamine or morpholine be employed in the refrigerant, but the duct extending from the aspirator assembly, to the condenser may be heated in the manner disclosed.

In order to separate sludge which has formed in a system of this character, the cooler is preferably arranged so that this sludge may drain to a suitable separator. Such a separator may be arranged so that refrigerant is evaporatod from the sludge due to heat and/or suction and/or so that the sludge is subjected to a substantial pressure or liquid head which results in squeezing the refrigerant out ofthe sludge. I

In some respects the present invention involves features disclosed in my copending application Serial No. l7l,324, filed October 27, 1937, and in general the present application discloses an improved system of the general type disclosed in my copending application Serial No. 171,325, flied October 2'7, 1937.

It should be understood that the present disclosure is for the purpose of illustration only ad that this invention includes all modifications .nd equivalents which fall within'the scope of the appended claims.

I claim:

l. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant cir-v cuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said cooler having lower wall parts sloping downwardly, and a sludge separator connected to the bottom of 'the cooler for receiving sludge therefrom and for separating the sludge into propellant and refrigerant.

2. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor .is effective in entraining refrigerant vapor from the cooler and pumping the same'to the condenser, said cooler having lower wall parts sloping downwardly, and a sludge separator connected to the bottom of the cooler for receiving'sludge therefrom and for separating v the sludge into propellant and refrigerant, said separator being in the form of a downwardly extending duct wherein the sludge may collect 2,174.,soo

to more sufflcient liquid head to cause the sepathe sludge into propellant and refrigerant, said separator including achamber having a smaller cross sectional area near its lower end than at its upper end.

4. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant cirpor from the cooler and pumping the same .to

the condenser, said cooler having lower wall parts sloping downwardly, and a. sludge separator connected to the bottom of the cooler for receiving sludge therefrom and for separating the sludge into propellant and refrigerant, said separator being in the form of a downwardly extending duct wherein the sludge may collect to afford suflicient liquid head to cause the separation of the sludge under pressure, a second duct extending upwardly from said first-named ductto cooperate therewith in forming a trap, a pipe for returning propellant to the vaporizer, said second duct having a connection with said pipe.

5. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor iseffective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, and means associated with the refrigerant circuit for preventing the formation of sludge in the condenser.

6. Refrigerating apparatus of the class described comprising arefrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing a body of liquid propellant in the form of mercury, said refrigerant circuit including a duct between said common part and the refrigerant condenser, said duct being juxtaposed to a warm portion of the system whereby the formation of sludge in the condenser is impeded.

'l. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing a body of liquid propellant, means associated with the refrigerant circuit to prevent the formation of sludge in the condenser, and means to receive sludge which forms in the cooler and to break up sludge thus received.

.a sludge does not collect to choke either of said circuits,

9. Refrigerating apparatus comprising a r-- frieerant circuit inoludintr a cooler and a refrie erant condenser, a propellant circuit inclue a vaporizer and a part in coon with said re friserant circuit wherein refrigerant vapor from the cooler is entrained in a stream of the propellant vapor, said vaporlaer containing a body ofliquid mercury, said cooler containing a body of liquid refrigerant which tends to interact with the mercury to form a sludge, and means to receive sludge from the cooler and to hreals up said sludge.

-10. Low temperature refriecratine: apparatus comprising a refrigerant circuit having, a low pressure portion including a cooler and having a high pressure portion includine a condenser. a propellant circuit including a vaporizer and a part in common with said refrigerant circuit wherein refrigerant vapor from the cooler is entrained in a stream of propellant vapor. from the vaporizer, said cooler containing a hasty of aqueous refrigerant composed of water and an anti-freeze agent to depress the freezing pointof the refrigerant, the anti freeze agent tending to cause the formation of a sludge by the refrigerant and the mercury, a drain connected to the cooler to receive sludge therefrom, a chamber connected to the drain, a duct con necting the chamber to the low pressure portion of the refrigerant circuit so that refrigerant vapor is drawn from the sludge in said chamber.

11. Refrigerating apparatus comprising a refrigerant circuit having a low pressure portion including a cooler and having a high pressure portion including a, condenser, a propellant circuit including a vaporizer and a part in common with said refrigerant circuit wherein refrigerant vapor from the cooler is entrained in a stream of the propellant vapor from thevaporizer, said vaporizer containing a body of mercury, said cooler containing a body of refrigerant which may interact with mercury to form a. sludge, a chamber connected to the cooler to receive sludge therefrom, said chamber communicating with the common part of said circuits so that refrigerant ing vapor of the stream and directing the resultingkcondensate back to the cooler, removing from the cooler" sludge formed by mercury and the refrigerant, drawing refrigerant vapor from the sludge by entrainment in the mercury vapor m stream, thus breaking up the sludga and returning the residue of mercury to the region of mercury vaporization.

13. Low temperature refrigerating apparatus comprising a refrigerant circuit including a cooler and a condenser; a propellant circuit including a vaporizer and a part in common with said refrigcram-circuit wherein refrigerant vapor from the cooler is entrained in a stream of propellant vaper from the vaporizer, said cooler containing a body of aqueous refrigerant, a drain connected to the cooler to receive sludge therefrom, a cham ber connected to the drain, .said chamber communicating with the common part of the circuits so that refrigerant vapor is drawn from the sludge in said chamber and entrained in the propellant vapor stream, the refrigerant circuitincluding a return duct extending from the condenser toa connection with said drain, so that the returning refrigerant may normally rise from said connection through the upper part of the drain to the cooler, the returning refrigerant passing through the lower part of the drain to the chamber and being vaporized when said upper part of the drain becomes choked with frozen refrigerant, the refrigerant thus received by the chamber being vaporized and drawn into said common part so that the rate of vaporization in the cooler is thereby automatically reduced.

it. Low temperature refrigerating apparatus comprising, a refrigerant circuit having a low pressure portion including a. cooler and having a high pressure portion including a condenser, a propellant circuit including a vaporizer and a part in common with said refrigerant circuit whereinlreirieerant vapor from the cooler is entrained in a stream of propellant vapor from the vaporizer, said cooler containing a body of aqueous refrigerant, a drain of relatively large diameter connected to the bottom of the cooler, the cooler having lower walls sloping downwardly toward the connection with the drain so that relatively thick: sludge may gravitate into the drain,

a chamber connected to the drain and to the low pressure portion of the refrigerant circuit, said chamber being arranged to receive sludge from the drain whereupon vapor is drawn from the sludge into said low pressure portion.

15. Refrigerating apparatus of the-class de scribed comprising a propellant circuit and a refrigerant circuit, said circuits having a part in common where propellant vapor pumps and compresses refrigerant vapor and wherein the propellant vapor is condensed, said propellant circuit also including a boiler, a pipe to direct propellaut vapor from, the boiler to said common part, and a return pipe to direct condensed propellant from said commonpart back to the boiler, said refrigerant circuit also including a refrigerant condenser and a, cooler, said propellant vapor normally pumping refrigerant vapor through said common part from a body of liquid refrigerant in the cooler, said system including piping arranged normally to supply liquid refrigerant from the refrigerant condenser to the cooler,'said piping being arranged so that when freezing of the refrigerant occurs therein adjoining the cooler, the condenser refrigerant may be supplied to a region from which it may be pumped by the propellant vapor in said common part, so that the proportion of vapor being pumped-from the cooler is automatically reduced and the temperature of the cooler is automatically increased to melt the frozen refrigerant. v

16. Refrigerating apparatus comprising a refrigerant circuit having a low pressure portion -of the propellant vapor from the vaporizer, saidvaporizer containing a body of mercury, a return duct extending from-the condenser to the cooler, a chamber, a trap between the duct and the chamber, said trap normally preventing flow of refrigerant from the duct to the chamber but permitting such flow when refrigerant freezes to prevent flow through the duct to the cooler, and a pipe connecting the chamber to the low pressure portion of the refrigerant circuit so that refrigerant vapor may be drawn from the chamber thereby causing an automatic reduction of the rate of evaporation in the cooler.

17. Method of refrigeration comprising continuously entraining refrigerant vapor from a cooler in a propellant vapor stream, condensing propellant out of the 'resulting mixed vapors, separately condensing the refrigerant, and returning the condensed refrigerant to the cooler until the temperature of the cooler falls below a predetermined point, thereupon diverting the condensed refrigerant from the cooler, and drawing refrigerant vapor from the diverted refrigerant by entrainment in the propellant vapor stream, thus employing part of the energy of the propellant vapor stream to pump refrigerant vapor from a region outside of the cooler when the, cooler has reached an undesirably low temperature.

18. Refrigerating apparatus comprising a refrigerant circuit having a low pressure portion including a cooler and having a high pressure portion including a condenser, a propellant circuit including a vaporizer and a part in common with said refrigerant circuit wherein refrigerant vapor from the cooler is entrained in a stream of the propellant vapor from the vaporizer, said vaporizer containing a body of mercury, a return duct extending from the condenser to the cooler, said duct having a trap with a pressure balancing column of propellant in one leg, a section of the ductextending downwardly from said leg to a connection to the cooler below the latter, means connected to said trap automatically to vary the height of the pressure balancing column in response to changes in the pressure difference between the cooler and condenser, a chamber arranged to receive sludge from said connection. and a pipe connecting the chamber to the low pressure portion of said refrigerant circuit, whereby the refrigerant may be drawn from the sludge.

19. Method of refrigeration comprising vaporizing mercury to provide a mercury vapor stream, entraining refrigerant vapor from a region of refrigeration in the mercury vapor stream, condensing the major portion of the mercury out of the resulting stream of mixed vapors, separately condensing the remaining vapor and removing from the resulting condensate sludge formed by mercury and the refrigerant, vaporizing refrigerant from the removed sludge at a point separated from said region, thus breaking up the sludge and returning the mercury residue from said point to the region of vaporization.

20. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, the propellant circuit also including a vapor pipe between the vaporizer and said common part, said refrigerant circuit including a duct between said common part and the refrigerant condenser, said duct having a portion in heat transfer relation to said vapor pipe, whereby said duct is heated and the formation of sludge in the condenser is impeded.

21. Refrigerating apparatus of the class described comprising a refrigerant circuit/including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizencontaining a body of liquid propellant in the form of mercury, said propellant circuit including a riser pipe through which mercury vapor passes from the vaporizer to said common part, the refrigerant circuit including a duct extending from the common part to the refrigerant condenser, a portion of said duct and said riser pipe being in heat transfer relation whereby the duct is heated and formation of sludge in the condenser is impeded.

22. Refrigerating apparatus of the class described comprising arefrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing a body of liquid propellant in the form of mercury, said cooler containing a body of refrigerant comprising a solution of the mono methyl ether of ethylene glycol, which may interact with mercury particles to form a sludge, the refrigerant circuit including a duct extending from the common part to the condenser, said duct being in heat transfer rela- I tion to a warm portion of the system to impede the formation of sludge by such interaction of the refrigerant vapor and mercury.

23. Refrigerating apparatus of the class de-- scribed comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vaporis effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing a body of liquid propellant in the "form of mercury, means associated with the refrigerant circuit to prevent the formation of sludge in thecondenser, and means to receive sludge which forms in the cooler and to break up sludge thus received, said lastnamed means including a chamber and a duct through which the chamber communicates with said common part of the circuit so that refrigerant vapor is drawn from the sludge in said chamber.

24. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing liquid propellant, a chamber arranged to receive sludge from the cooler, said chamber containing a body of liquid propellant and having an overflow connection through which propellant may pass to be nected to the lower part returned to the vaporizer, said connebtion being arranged so that the liquid body is maintained at a predetermined level in the chamber whereby foreign particles from the cooler may pass into the chamber and remain in the same while floating on the surface of the liquid body.

25. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a' propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective 'in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing liquid propellant in the form of mercury, a trap normally containing a body of mercury having one leg con- I of the cooler. a duct connecting the opposite leg of the trap with the common part of said circuits, means providing a spill-over connection from which mercury may return from the trap to the vaporizer, said spillover connection determining the normal level of mercury in the trap and being arranged so that the body of mercury is permanently re-- tained therein, the trap being arranged so that sludge .i'rom the cooler may pass through the trap and so that refrigerant vapor is drawn from the sludge, leaving the mercury residue in the trap. Y

26. Refrigerating apparatus of the class described comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with the refrigerant circuit where propellant vapor is effective in entraining refrigerant vapor from the cooler and pumping the same to the condenser, said vaporizer containing a-body of liquid propellant in the form of mercury, a a leg connected to the lower part of the cooler, theoppositelegofthetrapbeingarrangedtoreceive material draining from the cooler, a spillover connection associated with said last-named legsothatabodyofliquidmercuryispermanentlyretained ataleveiinsaid leg, whereby from said 1 connection,

having densing the major portion of the mercury out of the resulting stream of mixed vapors, then directing the remaining vapor past a surface while heating the surface and then condensing the remaining vapor and directing the resulting condensate back to the region of refrigeration, whereby refrigeration is produced and theformation of sludge in thecondensate returning to the region of refrigeration is impeded.

28. Low temperature refrigerating apparatus comprising a refrigerant circuit including a cooler and a condenser, a propellant circuit including a vaporizer and a part in common with said refrigerant circuit wherein refrigerant vapor from the cooler is entrained in a stream of propellant vapor from the vaporizer, said cooler containing a body of aqueous refrigerant, a drain of relatively large diameter connected to the cooler, a return pipe in the refrigerant circuit extending from the condenser to a connection with said drain 'below the cooler,,the lower part of the drain providing a propellant-containing trap, a chamber connected to the leg of the trap remote said chamber communicating with the common part of said circuits, whereby sludge from the cooler may displace propellant in said trap and pass to the chamber and whereby refrigerant may displace propellant in-the trap and pass to the chamber when the drain is choked with frozen refrigerant adjoining the cooler, and whereby refrigerant under either of these conditions may be drawn from said chamber to the common part, and a. pipe through which propellant may flow from the chamber to the vaporizer, said pipe containing a columnof the propellant to balance the vaporizer pressure, an overflow connection between said chamber and the last-named 'pipe determining the height of the-propellant in said trap;

V LYMAN I". 'WHII'NEY. 

